If you can imagine a shrimp that swims free as an infant, and then decides to fix himself to a rock and create for himself a protective shell for the rest of his life. A rock or a whale or a boat or a crab - then you've got a barnacle. This shell is made of the same material as a lobster's exoskeleton, so although the shell resembles nothing like other crustaceans, it comes from the same biological process.

This is how most barnacles go about their lives. When safe in the protection of a high tide, the animal sticks its feet out to collect plankton.

This is the case for most, but not all barnacles, and when Charles Darwin found a barnacle that didn't conform, the entire world changed, forever.

Charles Darwin did not come up with his concept of the origin of species out of the blue. His grandfather, for one - a man by the name of Erasmus Darwin, was one of the most respected intellectuals of his age. He did more than touch on the ideas of evolution that Darwin would eventually set in stone.

The ideas of a more complicated biological world were already out there. Even Darwin's friend, Robert Grant, a doctor who had a passion for sea sponges, was influenced by Erasmus' texts on evolution. Robert Grant's sea sponges were considered plants, not animals, and the law of the world - even the scientific world - was that all living organisms were fixed, ordained by God.

Darwin often walked with Robert Grant along the seashore, digging through tide pools and looking for new things. These sea sponge conversations, and the wildly excitable crowd of England and Scotland's scientific elite got Darwin thinking.

But what really set things off was when Darwin was walking on the shores of Chile, and found a shell with tiny holes cut into it. Now, when Darwin was invited to explore the world, he was essentially just a kid. An extremely lucky kid who by inheritance and luck and curiosity, was allowed to join a mission to the strangest ends of Earth. So by questioning those holes in that shell, Darwin set off a train of thought that would last his lifetime.

Upon further examination, he found that the holes were created by a tiny barnacle. An unknown species. From then until his conclusions much later in life, Darwin focused on the barnacle. His findings were, well, perverse.

Darwin, long before his evolutionary findings, committed much of his life to the study of barnacles. What interested him was largely their sexuality. Many species were hermaphrodites, but others bisexual. In some cases the males were mere sacs of sperm who had no other purpose than to impregnate the female. In others, the males were like tiny bugs that lived on the skin of the female's body.

In all of this was Darwin's first eye openings into actual evidence for an evolution theory. Not finches or Galapagos Turtles or marine iguanas. Rather, the sexual lives of barnacles. If there seems to be a pattern of the creation of maleness in barnacles - or rather if different species of barnacles have different levels of hermaphroditism and sexuality, then perhaps...just perhaps there is a connection. Perhaps these creatures are thumbnails of early evolution.